1. Field of the Invention
This invention relates to an angle-measuring method, and an angle-measuring gyroscope system for implementing the same.
2. Description of the Related Art
FIG. 1 illustrates a conventional angle-measuring gyroscope system 1 that includes a gyroscope 11, a sensing module 12, and a calculating module 13.
As illustrated in FIGS. 2A and 2B, the gyroscope 11 includes a proof mass 111 that oscillates in an x-y plane. As the gyroscope 11 rotates about an axis orthogonal to the x-y plane, an axis of oscillation (V) of the proof mass 111 precesses.
The sensing module 12 detects motion of the proof mass 111, and generates a set of sensing signals that correspond to the motion of the proof mass 111 detected thereby.
The calculating module 13 calculates an angle of rotation (φ) of the gyroscope 11 either based directly on the sensing signals or by calculating first an angular rate based on the sensing signals, followed by integrating the angular rate.
The angle of rotation (φ) calculated by the conventional angle-measuring gyroscope system 1, however, is inaccurate. This is due to defects in the gyroscope 11 and the sensing module 12 and noise in and signal drift of the sensing signals.
Several techniques have been proposed to alleviate the aforementioned problems. These conventional techniques, however, have drawbacks. For instance, the technique, such as that disclosed in U.S. Pat. Nos. 6,481,285 and 6,928,874, requires a complex structure and calibrations to minimize the effect of defects in a gyroscope. Moreover, the technique, such as that disclosed in “A low noise capacitive sensing amplifier for CMOS-MEMS gyroscope with 1 milli-watt power dissipation,” Proceedings of the Second International Workshop on Network Sensing Systems, p. 119-123, 2005, requires a complex circuit design. Further, the technique, such as that disclosed in U.S. Pat. Nos. 6,481,285, 6,928,874, and 6,934660, “New adaptive mode of operation for MEMS gyroscopes,” Journal of Dynamic Systems, 4th quarter, vol. 126, p. 800-810, 2004, and “Dynamics and control of a MEMS angle measuring gyroscope,” Sensors and Actuators A, 1st quarter, vol. 144, p. 56-63, 2008, which calculates a set of control signals based on a set of sensing signals for controlling oscillation of a proof mass to thereby compensate the effect of defects in a gyroscope, fails to minimize the effect of defects in a sensing module and signal drift of the sensing signals.